Humans Are Being Taught to Echolo­cate Like Dol­phins — and It’s Sur­pris­ingly Easy

Sci­en­tists have suc­cess­fully taught a small group of blind and sighted peo­ple how to nav­i­gate their sur­round­ings using echolo­ca­tion — the sonar-​based lan­guage of dol­phins and bats. Using sound cre­ated by tongue clicks, the group learned how to detect the size of vir­tual rooms with sur­pris­ing accu­racy — some­thing that researchers had not expected in peo­ple who were born with sight. While blind peo­ple have proven suc­cess­ful at echolo­ca­tion in the past, it’s been unclear if sighted peo­ple can develop the same abil­ity, given their almost total depen­dence on visual perception.

“We thought, ‘If it’s sighted peo­ple, it’s not going to be some­thing we’ve ever learned to do, so prob­a­bly we’re really bad at it,’” one of the team, Vir­ginia Flana­gin from the Lud­wig Max­i­m­il­ian Uni­ver­sity of Munich, Ger­many, told Veronique Green­wood at The Atlantic. But the results showed the oppo­site — in an exper­i­ment involv­ing 11 sighted peo­ple and one blind per­son, the best-​performing sighted per­son could use echolo­ca­tion to detect a mere 4 per­cent dif­fer­ence in the size of a vir­tual room. “Even the peo­ple who did less well could still often tell apart dif­fer­ences of 6 to 8 per­cent, with the least skilled bot­tom­ing out at a 16 per­cent dif­fer­ence,” Green­wood reports. “Over­all, that actu­ally is about the same level of acu­ity — abil­ity to dis­tin­guish dif­fer­ences — that you find in some visual tests, says Flana­gin.” To fig­ure this out, the team first trained their sub­jects in echolo­ca­tion by plac­ing them in a heav­ily padded ane­choic cham­ber, and play­ing record­ings of clicks made pre­vi­ously in real-​life build­ings. By run­ning the exer­cise in a room that pro­duces no echoes of its own, the researchers could tell the par­tic­i­pants which sounds cor­re­lated to larger or smaller rooms, giv­ing them the oppor­tu­nity to learn the sub­tle dif­fer­ences between the two. Once the vol­un­teers had got­ten through the ini­tial train­ing, the team hooked them into an MRI machine, which was con­nected to a vir­tual, 3D model of a nearby chapel build­ing. The vol­un­teers would either click their tongue to make a sound, or the machine would make the sound for them — referred to as “active” and “pas­sive” echolo­ca­tion — and lis­ten for how those sounds echoed through the vir­tual room. Based on these echoes, the vol­un­teers would have to judge the size of the vir­tual room. The researchers found that the vol­un­teers all did sig­nif­i­cantly bet­ter when they were per­form­ing active echolo­ca­tion — mean­ing their own clicks were a far more effec­tive tool for them to nav­i­gate their vir­tual sur­round­ings. That makes sense, see­ing as the vol­un­teers were more actively engaged in the exha­la­tion when they were the ones per­form­ing it, but what the researchers found strange was that the sound of the echoes acti­vated the sighted vol­un­teers’ motor cor­tex — the region of the brain respon­si­ble for move­ment. Even when the team com­pared MRI scans from active and pas­sive echolo­ca­tion — allow­ing them to iso­late and remove the brain activ­ity involved in actu­ally mak­ing the phys­i­cal click­ing sound — that part of the brain still showed signs of life. In fact, the motor cor­tex was found to be most active with large ver­sions of the chapel than smaller ones, Green­wood reports, which sug­gests a con­nec­tion between vir­tu­ally nav­i­gat­ing and phys­i­cally nav­i­gat­ing a space. “It seems like the motor cor­tex is some­how involved in the sen­sory pro­cess­ing,” Flana­gin told her. In the blind sub­ject, the echoes acti­vated the unused visual cor­tex instead, sug­gest­ing that they were visu­al­is­ing the echoes as they bounced between the vir­tual walls. We should note that the study is extremely small, with a lim­ited sam­ple size of both blind and sighted peo­ple, so we can’t read too much into the results until they have been repli­cated in a much larger, more diverse group. But based on what we know about human echolo­ca­tion already, it sug­gests that sighted peo­ple do have the capac­ity for this purely sound-​based form of nav­i­ga­tion. You can watch one of the most famous human echolo­ca­tion experts, Daniel Kish, demon­strate his abil­ity rid­ing a bike in the video below: The research has been pub­lished in the Jour­nal of Neu­ro­science.

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